Biology 200 Section 105 Midterm Exam ( October 14, 2008) (Answer Key) If there are any marking mistakes in your exam, I can remark it. If you want that I remark your exam : 1. Please compare your exam to the answer key posted on the VISTA site. 2. Please put in writing your request, attach it to the exam and give it to me. 3. Leave the exam (with writing request) with me during class, or office hours. 4. I will remark the whole exam, so marks can go up or marks can go down!! Please handle all exams with requests to me by Thursday, November 6 th , at 1:00 pm. ) Here is a short section of DNA template strand. a. (2 marks) Transcribe and translate this sequence. b. (1 mark) Label the 3’ and 5’ ends of mRNA. c. (1 mark) Label the N and C terminals of the protein. DNA: 3’ G G T G G T A C C C C T C A G A G T C G T T T C T T 5’ mRNA: 5’ C C A C C A U G G G G A G U C U C A G C A A A G A A 3’ N | Met | Gly | Ser | Leu | Ser | Lys | Glu | C d. (2 marks) If this protein was isolated from a cell, what amino acid would be at the N terminal end of the peptide? Explain why. Glycine because the Met found at the N terminal of the newly made protein is cleaved. e. (2 marks) What would be the result if an A was inserted in the DNA following the G shown in boldface and underlined? An UAG stop codon would be formed, and the peptide would terminate with Leu . Question 2 (white exam) Question 5 (yellow exam). (5 marks, 5 minutes) Phospholipids form sealed spherical vesicles (liposomes) in water. Assume that you have constructed liposomes that contain Na +-K + pumps with the portion of the molecule that normally faces the cytosol oriented towards the outside of the liposomes. What would happen if: a. (1 mark) Your liposomes were suspended in a solution containing both Na + and K + ions and had a solution with the same ionic composition inside? Explain briefly. Nothing would happen as without ATP the pump would not work. b. (2 marks) You add ATP to the suspension described in (a). Explain briefly. If ATP is added, the pump would be turned on. Na+ ions would be pumped into the liposomes and K+

This preview
has intentionally blurred sections.
Sign up to view the full version.